Good try but it was the DfT accessibility (slam doors) deadline that did it.
Nevertheless, this sort of thing demonstrates why the 1950s option of retaining old stock, mouldering in sidings for 90% of the year, is no longer credible. There have been steady changes to requirements - asbestos, crashworthiness, retention toilets, information screens, door locking then power doors and so on. And on today's fixed formation/multiple unit railway every cab has to keep up with communications, data logging, balise reading, ERTMS/ETCS, etc.. The inexorable march of obsolescence, quite apart from other challenges such as security of idle stock.